Cleanup: Use default constructor for WebCryptoKey rather than createNull() factory method.

content/child/webcrypto/test/aes_gcm_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/stl_util.h"
 #include "content/child/webcrypto/algorithm_dispatch.h"
 #include "content/child/webcrypto/crypto_data.h"
 #include "content/child/webcrypto/status.h"
 #include "content/child/webcrypto/test/test_helpers.h"
 #include "content/child/webcrypto/webcrypto_util.h"
@@ skipping 91 matching lines @@
   return Decrypt(algorithm, key, CryptoData(cipher_text_with_tag), plain_text);
 }
 
 TEST(WebCryptoAesGcmTest, GenerateKeyBadLength) {
   if (!SupportsAesGcm()) {
     LOG(WARNING) << "AES GCM not supported, skipping tests";
     return;
   }
 
   const unsigned short kKeyLen[] = {0, 127, 257};
-  blink::WebCryptoKey key = blink::WebCryptoKey::createNull();
+  blink::WebCryptoKey key;
   for (size_t i = 0; i < arraysize(kKeyLen); ++i) {
     SCOPED_TRACE(i);
     EXPECT_EQ(Status::ErrorGenerateKeyLength(),
               GenerateSecretKey(
                   CreateAesGcmKeyGenAlgorithm(kKeyLen[i]), true, 0, &key));
   }
 }
 
 TEST(WebCryptoAesGcmTest, ImportExportJwk) {
   // Some Linux test runners may not have a new enough version of NSS.
@@ skipping 138 matching lines @@
                               &plain_text));
     }
   }
 }
 
 }  // namespace
 
 }  // namespace webcrypto
 
 }  // namespace content